1. Field of the Invention
The present invention generally relates to a semiconductor device, in particular, to a microelectromechanical system microphone structure and a microelectromechanical system microphone package structure.
2. Description of Related Art
Microelectromechanical System Device (MEMS device) refers to a microelectromechanical device manufactured in a miniaturized package structure with a technology extremely similar to a technology for manufacturing an integrated circuit (IC). However, the MEMS device interacts with a surrounding environment in more manners than a conventional IC, such as interaction in mechanics, optics, or magnetic force. The MEMS device includes tiny electromechanical devices, such as an accelerometer, a switch, a capacitor, an inductor, and a microphone. The MEMS device manufactured with an MEMS technology has many advantages. For example, an MEMS microphone manufactured with the MEMS technology has features of light weight, small volume, and preferred signal quality. Therefore, the MEMS microphone gradually becomes the mainstream of microphones.
Generally speaking, the MEMS microphone has been improved both in reception efficiency and stability, and can provide clear and fluent voice quality either in a noisy environment or in high-speed movement. However, since a diaphragm for reception is a plane, phase noises are caused, i.e., a sounder and surrounding environmental noises may be heard by a receiver, so the receiver is interfered when understanding an audio message. On the contrary, a directional microphone is provided with a function of distinguish the direction of a sound source, which may enhance the intensity of sound in a specific direction and reduce the intensity of sound from other directions, so that the receiver may hear a clear and correct audio message. Therefore, along with the rapid development of personal electronic products such as mobile phones, personal digital assistants (PDAs), notebooks, and hearing aids, an MEMS microphone with a directional function is in urgent need in the industry.